Dyeing of fabrics comprising cellulose acetate with an alcohol-thiocyanate swelling mixture



Patented Oct. 14, 1947 2,428,885 1 DYEING F FABRICS COMPRISING CELLU- LOSE ACETATE WITH AN ALCOHOL-TRIO- CYANATE SWELLIN G MIXTURE Cyril M. Croft and Walter H. Hlndlc, Cumberland,

BClahns. 1

This invention relates to the coloration of orsanic derivative of cellulose textile materials, and relates more particularly to the coloration of organic derivative of cellulose textile materials by processes involving the application of mechani-.

cal impregnation methods.

An object of our invention is to provide an improved process for the dyeing of organic derivative of cellulose textile materials.

Another object of our invention is the provision of a solvent dyeing process for organic derivative of cellulose materials involving the application of mechanical impregnation methods, which process is not onlyirapid but highly economical as well. a

A further object. of our invention is the provision of a process particularly adapted to the dyein'g of organic derivative of cellulose textile materials employing dyestuffs which, when applied by the usual methods, do not possess any pronounced affinity for organic derivative of cellulose materials.

Yet another object of our invention is the provision of a solvent dyeing process for the dyeingof organic derivative of cellulose materials which eliminates the necessity of rapid drying of the dyed materials before the latter may be washed and finished and which yields dyed materials exhibiting unusual resistance to acid fading.

Other objects of our invention will appear from the following detailed description.

In the coloration of textile materials it is most advantageous, from'an economic point of view, to effect the desired coloration of the textile material in as short a time and with as little handling of the material as possible. When dyeing organic derivative of cellulose materials, it has been found that these materials are dyed more slowly than other textile materials since they are,

less absorbent and the dye llquor'in the dye bath does not penetrate them as rapidly or as completely as it does other textile materials. Many dyestuils when applied to organic derivative of cellulose materials yield satisfactory dyeings in deep, non-fugitive shades only after long. periods of immersion and manipulation. In some instances, where solvent dyeing methods are employed in order to speed up the dyeing operation, a rapid drying of the dyed organic derivative of cellulose material is necessary in order to obtain fast colorations which will not wash down to lighter shades on subsequent scouring.

We have now discovered that organic derivative of. cellulose materials may be dyed rapidly in deep, fast, level shades by mechanical impregnaassign'ors to Celan America, a corporation of Delaware No Drawing. Application October 21, 194:, Serial No. 507,154

ese Corporation of tlon methods employing aqueous alcoholic solutions of dyestuffs for said organic derivative of cellulose materials, without the necessity of sub- Jecting said dyed materials to the step of rapid drying before the materials may be washed and finished. In accordance with our novel process,

the drying step may be eliminated and fast dyeings obtained directly if thedyebath employed for dyeing the organic derivative of cellulose materials comprises an aqueous alcoholic solution of the desired dyestuil containing an inorganic swelling agent for the organic derivative of cellulose material and, preferably, in addition thereto a lower aliphatic acid. Employing such dyebaths and applying them by mechanical impregnation methods enables the organic derivative of cellulose materials to'be dyed very rapidly. The dyed materials may be washed or scoured immediately after dyeing without suflering from any appreciable loss in color. greatly increases dyeing efficiency which is reflected by 'the marked increase in the capacity of the plant which is achieved with greatly reduced cost. Furthermore, it has been observed that the organic derivative of cellulose materials dyed by the process of our invention exhibit greatly improved resistance to acid fading.

As examples oi inorganic swelling agents for the organic derivative of cellulose materials, there may be mentioned the salts of thiocyanic acid such as ammonium thiocyanate, sodium thiocyanate and potassium thiocyanate. Optimum results are achieved employing sodium thiocyanate. The inorganic swelling agent may be present'in amountsof from 1.0 to 3.0% on the weight of the dyebath. Preferably, we employ from 1.8 to 2.2% by weight.

The lower aliphatic alcohols which are suitable for use in forming the dyebath are those alcohols which are solvents for the dyestuffs employed and which exert at least a swelling or softening action on the organic derivatives of cellulose. we prefer to employ ethyl alcohol in the dye liquor, other alcohols such as methyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, secondary butyl;alcohol, tertiary butyl alcohol, n-amyl alcohol, secondary amyl alcohol and tertiary amyl alcohol, or mixtures of these alcohols may be used. The amount of the alcohol used in the dye liquor will vary depending upon the alcohol or alcohols used. We. have found that optimum results are obtained when the lower aliphatic alcohol comprisesat least by weight of the dyebath. Any suitable lower aliphatic acid may be employed in the dyebath. Examples of This substantial advantage While I these acids are acetic acid, propionic acid and butyric acid. The acid may be employed in amounts varying from 1 to about 8% by weight, optimum results being achieved when the acid is present in the dyebath in amountsof from 2.0 to 5.0%by Weight.

Various dyestuffs for organic derivative of cellulose materials may be employed. The dyestufls passed through a solution of the dyestuif, then between nippingrolls of a padding mangle which are adjusted to permit the desired amountof dye liquor to be retained in the fabric, and the fabric then subjected directly to washing or scouring.

In the case of fabrics dyed with'the sulfuricacid esters of leuco vat dyes, however, the fabric is may be direct dyeing dyestuffs, for example, those dyes which produce their ultimate shade on the material being dyed without any preor aftertreatment designed to effect a chemical change" in the structure of the dye or thecharacter of the immersed in a suitable oxidizing bath to oxidize the leuco dye to the colored form prior to wash ing. The duration of the immersion of the fabric in the dye liquor is relatively short and may be from 1 to 6 seconds.

. be processed through the padding mangle at material being dyed, or the dyes maybe dyestuffs such as the sulfuric acid esters of leuco vat dyestuffs which are applied incolorless form and are oxidized back to the colored form after being applied to the organic derivative of cellulose materials. The direct dyeing dyestuffs may be acid dyes which are ordinarily used for the dyeing of wool and which do not possess any substantial ods in alcoholic solutions containing a lower allspeeds ranging up to 60 yards per. minute. a Our process is applicable not only-to the dyeing of fabrics but particularly valuable results are obtained when other organic derivative of celluphatic acid and an inorganic swelling agent, in

accordance with our process, the resulting dyeings are of uniform depth and unusual brilliance and may be obtained with a relatively short immersion time. Preferably, when employing sulfuric acid esters of leuco vat dyes in accordance with our 'novel process, the lower aliphatic acid is advantageously omitted from the dyebath to avoid any premature oxidation of the leuco dye. The washdown of the shade in subsequent washing and finishing operations is considerably less in the case of fabrics dyed by our novel process than in the case of fabrics dyed by prior processes. Furthermore, many shades obtained are considerably faster to acid fading than the shades obtained by prior processes employing the same dyestuffs. Especially advantageous results may be obtained when dischargeable acid dyestuffs are employed. Fabrics which have been dyed with dischargeable acid dyes may then be discharge printed employing hydrosulfite discharging agents and, if desired, the discharged area may be simultaneously illuminated by employing any suitable dyestuff in the discharge composition as, for example, the vat dyestuffs. Fabrics dyed with dischargeable acid dyestuffs and then discharged with or Without illumination also exhibit unusual resistance to'acid fading, Another very substantial advantage of our novel process lies in the fact that the formation of warp streaks, a fault frequently observed when employing acid dyestuffs,

is very greatly minimized and no longer presents,

any particular problem.

Theamount of dyestuffs dissolved in the dyebath will, of course, vary with the final shade desired in the material which is being dyed and may be from as lowas 0.01% up to 5.0% basedon the weight of the material to be dyed. l

The dyebath may be applied to the organic derivative of cellulose textile materials by padding, spraying or by other convenient method of mechanical impregnation. Thus, as a continuous process, a fabric may be unwound from a roll,

lose textile materials such as staple fiber, in the form of a top or roving, is dyed in accordancewith our invention. Not only may more uniform dyeings be obtained but, as in the case of fabrics,

of cellulose esters are cellulose acetate, cellulose propionate, cellulose butyrate, and mixed esters such as cellulose acetate-propionate and cellulose acetate-butyrate, while examples of cellulose ethers are ethyl cellulose and benzyl cellulose.

The materials may be mixed materials containing organic derivatives of cellulose and yarns or fibers of other materials such as cotton, silk, wool or regenerated cellulose-and in this way differential dyeings may be obtained where the dyes used have an aflinity for only one of the components of the mixed textile material.

In order further to illustrate our inventionbut without being limited thereto the follow'in'g examples are given:

Example I A mixture comprising 1'7 parts by weight of l-methylamino-4-iso propylamino 2 carboxyamide-anthraquinone, 2.25iparts by weight of 2-chlor-4-nitro 6-brom-benzene-azo-dioxyethyl metachlor-aniline and 0.75 part by weight of 1- hydroxy-4-amino-anthraquinone are dissolved in a solvent bath j comprising 532 parts by weight I of ethyl alcohol, 31.5 parts by weight of acetic acid, 20 parts by weight of sodium thiocyanate and 298 parts by weight of water to form the dyebath. A cellulose acetate fabric is pad dyed employing this dyebath at a rate of 20 yards per minute and is dyed a dark gray-blue color.

The dyed fabric'is washed immediately while still wet from the dyeing operation and no change'in shade resultsfrfom the washing.

I I '5 Eaample II 25 ,partsby weight of A20 Rubinol (an aciddye) aredissolved in a mixture comprising 266parts byuweight of ethyl alcohol, 15.75 parts by-weight of acetic acid, 10 parts by weight of sodium thiocyanate andj149 parts by weight of water ,to form the dyebath. A cellulose acetate fabric of sharkskin weave is pad dyedwith this. dyebath at a rate of about 20 yards per minute and the fabric isfdyed a red shade. 'The' dyed fabric is washedwith water immediately without loss of :color and. exhibits excellent light fastness.

If desired, the fabric may i Example 1!! A mixture of 15 parts by weight of Xylene Milling Blue GL (Color Index No. 833), 2.5 parts by weight of 2-chlor-4-nitro-6-brom-benzene-azodioxyethyl-meta-chlor-aniline and 0.5 part by weight of 1-hydroxy-4-amino-anthraquinone are dissolved in a mixture of 532 parts by weighto! ethyl alcohol, 31.5 parts by weight-of acetic acid, 20 parts by weight of sodium thiocyanate and 298 parts by weight of water to form the desired dyebath. A scoured cellulose acetate fabric is pad dyed with this dyebath at the rate of 20 yards per minute and washed with water immediately after dyeing. The dyed fabric exhibits excellent resistance to light and acid fading.

Example IV parts by weight of Ponsol blue BF (a leuco vat dye in sulfuric acid ester form) are dissolved in.400 parts by weight of ethyl alcohol and 20 parts by weight of sodium thiocyanate dissolved in 500 parts by weight of water are added to the alcoholic solution. A fabric woven of cellulose acetate and regenerated cellulose yarns is padded with the above dyebath and then passed directly into a 0.3% aqueous solution of sodium nitrite containing 0.1% of sulfuric acid-maintained at 35 C. The fabric is dyed an even shade of blue by this treatment and is then washed, neutralized,

scoured and dried. By varying the proportions of alcohol and water in the dyebath very desirable cross-dyed eifects may be produced. The dyed fabric is very resistant tolight and acid fading.

It is to be understood that the foregoing detailed description is given merely by way'of illustration and that many variations may be made therein without departing from the spirit or our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for the coloration of organic deriv- I ative of cellulose textile materials, which comprises mechanically impregnating such textile material with a solution of a dyestufi' capable of dyeing the organic derivative of cellulose material in an aqueous medium comprising at least by weight of a lower aliphatic alcohol and as an inorganic swelling agent for the organic derivative of cellulose material from 1.0 to 3.0% by weight of a salt of thiocyanic acid and immediately washing the wet textile material. 2. Process for the coloration of cellulose acetate textile materials, which comprises mechanically impregnating such textile material with a solution of a dyestuii capable of dyeing the cellu-' lose acetate material in an aqueous medium comprising at least 60% by weight of a lower aliphatic alcohol, and as an inorganic swelling agent for the cellulose acetate material from 1.0 to 3.0%

by weight of a salt of thiocyanic acid and immediately washing the textile material.

3. Process for the coloration of a cellulose acetate textile material, which comprises mechanically impregnating such textile material with'a solution of a direct dyeing dyestuff for the cellulose acetate material in an aqueous medium comprising at least 60% by weight of a lower aliphatic alcohol and containing from 2.0 to 5.0%

by weight of acetic acid and from .1.0 to 3.0% by weight of sodium thiocyanate and immediately washing the wet textile material.

4. Process for the coloration of a cellulose acetate textile material, which comprises mechanically impregnating such textile material with a solution of a direct dyeing dyestufl for thecellulose acetate material in an aqueous medium comprising at least 60% by. weight of ethyl alcohol and containing from 2.0 to 5.0% by weight of acetic'acid and from 1.0 to 3.0% by weight of sodium thiocyanate and immediately washing the 1 wet textile material.

5. Process for the coloration of cellulose acetate material in a fabric containing cellulose acetate fibers and other fibers, which comprises padding the fabric with an aqueous solution of a direct dyeing dyestufi for the cellulose acetate material comprising at least 60% by weight of a lower-aliphatic alcohol and containing from 1.0 to 8.0% by weight of a lower aliphatic acid and from 1.0 to 3.0% by weight of a salt of thiocyanic acid which is a swelling agent for the cellulose acetate material and immediately washing the wet textile material.

6. Process for. the coloration of a celluose acetate textile material, which comprises immersing such textile material for from 1 to 6 seconds in a solution of a direct dyeing dyestufi for the .cellulose acetate material in an aqueous'medium comprising about 60% by weight of ethyl alcohol,

'from 2 to 5% by weight of acetic acid and from 1 to 3% by weight af sodium thiocyanate, padding the dyed textile material, and then washing the wet textile material immediately after padding.

CYRIL M. CROFT. WALTER H. HINDLE.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PA'rE'NTs 

